A variety of power converters have been widely used to provide regulated voltages and currents to a variety of electronic products. Power converters have been required to meet power management and energy conservation standards based on environmental pollution constraints. The principle of power management is to manage the power consumption of the system during operation. During non-operational periods, only small amount of power will be consumed. Regarding the power converter in the power management application, in the light load state, saving power is the main demand nowadays.